Wednesday, June 10, 2009

Microarray Pin Drying Setup

Video 1. The NanoPrint microarray print design software is very flexible in that any combination of pins can be used to manufacture a microarray (1 to 48 pins), so creating dry station hardware to work with every pin combination is an extremely complex and difficult engineering problem. This is especially true if we want pins to dry pins very quickly to keep print run times as short as possible. It is common practice on the NanoPrint Microarrayer (and others that use our patented microarray pin printing technology) to use microplate foil sealing tape (as shown here drying 48 pins) to optimize the number of holes left open to match the pin tool configuration for any given print run. To simplify this process and to decrease the amount of time it takes to dry a set of pins, Arrayit has developed this simple alignment protocol using foil microplate tape (the same type used by pipetting robots that is designed to be pierced by pipette tips), an old micro spotting pin, and the “move to dry station” calibration command of the microarray robot. Listen to the sound in this video to the correctly configured sound that is made when the pins are at the dry station being dried, it is quiet when pins are drying and it is possible to hear the air flow when microarray pins are not drying. It is possible to program a wash protocol to have the dryer turned off when pins are washing and sonicating, but this option as been disable for this video to demonstrate the proper sound when pins are being dried. Also shown are both 946 and Stealth Style Microarray Pins, the procedure is compatible with Professional, 946 and Stealth Style Microarray Pins. If you do not have common microplate foil tape, contact Arrayit, it is easy to acquire. Note: depending on when your system was installed it may have a water level sensor or over flow tubing that looks different than what is shown in this video.

Protocol: This protocols is easy to do and takes only a few minutes. Read this all the way through before starting the procedure.

Step 1. Cover dry station holes with common foil microplate sealing tape, the type used to seal microplates which can be easily pierced by a pipette tip. Cut an even piece to cover all 48 holes on the dry station area and leave extra on the end to make it easy to remove when you want to make another pin configuration. Keep foil tape flat and press firmly into place. It is not difficult to remove when it is time to change the pin tool configuration.

Step 2. Remove all micro spotting pins from the NanoPrint Printhead. Using the NanoPrint control “move to command”, or movement command specific for your microarray robot, move the printhead to the calibrated operating dry station position.

Step 3. Using an old micro spotting pin (one not suitable for printing microarrays) place it into one of the pin hole locations you are planning to use for the new print run. Putting some pressure with your finger on top of the pin, push down on the pin in a manner to use the the pin to punch a hole into the foil sealing tape (see picture 3 below). This type of tape is designed to have holes punched into it, often used with pipetting robots. Push down firmly until the collar of the pin reaches the base of the printhead, leaving a hole in the foil tape. It is not difficult and does not require too hard of a push to punch the hole. Punch out holes only for the locations that match the pin tool configuration for the print run. The correct calibration location is with about 500 microns of the uptake channel showing above the foil seal, this height has been set during the installation of your machine. It does not have to be exact since the dry station using this method setup is very efficient. Note the difference in sound at the dry station with and without the foil tape setup. It is possible to program a wash protocol to have the dryer turned off when pins are washing and sonicating.

Step 4. Based on the calibration location set during the NanoPrint installation, it may be necessary raise the location of the pins at the wash station and/or sonicator station to make sure that liquid is not getting too high up on the shafts of the micro spotting pins. If the correct volume in source plates is being used, only the capillary tip area of the micro spotting pins need to be submerged in wash water at the sonicator and wash station positions.

Picture 1. Old microarray pin not used for printing in position to be pressed down to create proper dry station hole.

Picture 2. A gloved hand with finger pressing down old microarray pin to make a dry station hole. It does not take a lot of pressure to move pin all the way down so that the collar of the pin makes contact with the base of the printhead.

Picture 3. Position of pin after it has been pressed in showing the correct position for drying. The top of the uptake channel capillary of the micro spotting pin will be slightly visible. This position will force the air vacuum to be pull over the the tip of the pin only and dry it very quickly, within a few seconds. Only make holes that match the pin tool for a given print run, it does not take long to setup.

Picture 4. Picture 4. 48 holes as they appear completed.Only make the number of holes needed to match the pin configuration in a given print run, this setup procedure only takes a few minutes to setup for each pin configuration print run change.

For technical questions on this procedure contact: arrayit@arrayit.com or by phone at 408-744-1331